Mechanisms of MMP-Induced Malignancy in Breast Cells

描述(申请人提供)：基质金属蛋白酶(MMPs)是许多生理过程中必不可少的，但不适当的MMPs表达可促进肿瘤的发生和发展。对基质金属蛋白酶与恶性肿瘤之间关系的认识导致了广谱基质金属蛋白酶抑制剂作为癌症治疗药物的临床试验，但结果令人失望。临床试验的失败在很大程度上是由于基质金属蛋白酶抑制剂倾向于抑制必要的生理过程。靶向肿瘤特异性基质金属蛋白酶依赖效应的治疗策略可能被证明更有前途。以前的研究和我们的初步数据表明，乳腺上皮细胞暴露于选定的MMPs会导致细胞表面分子的裂解，从而刺激细胞产生活性氧物种(ROS)。依赖于基质金属蛋白酶的ROS的产生导致细胞经历上皮-间充质转化(EMT)，这是一种与进展到转移相关的基本表型变化，并损害细胞基因组的稳定性。我们的长期目标是确定与基质金属蛋白酶诱导的恶变相关的具体步骤，以确定潜在的治疗干预要点。为此，我们建议(1)确定刺激ROS发展的MMPs的蛋白水解靶；(2)确定转录因子Snail和Twist在基质金属蛋白酶/ROS诱导的EMT中的作用；(3)确定基质金属蛋白酶/ROS如何刺激基因组不稳定性。在目标1中，对基质金属蛋白酶切割E-钙粘蛋白的具体作用的研究将辅之以蛋白水解性筛选以寻找额外的/替代靶点。在目标2中，我们将确定导致Snail和Twist表达增加的基质金属蛋白酶诱导因子，并分析这些转录因子在基质金属蛋白酶诱导的子宫内膜转化中的相对作用。在目标3中，我们将研究MMP/ROS如何通过刺激中心体扩增来诱导细胞非整倍体和有丝分裂异常。我们期望通过阐明MMPs诱导EMT和基因组不稳定的一连串事件，我们将能够为乳腺癌的治疗干预找到新的有希望的点。

DESCRIPTION (provided by applicant): Matrix metalloproteinases (MMPs) are essential for many physiological processes, but inappropriate expression of MMPs can facilitate the development and progression of tumors. Recognition of the relationship between MMPs and malignancy led to clinical trials of broad-spectrum MMP inhibitors as cancer therapeutics, but the results were disappointing. The failure of the clinical trials was due in large part to the propensity of the MMP inhibitors to inhibit essential physiological processes. Therapeutic strategies that target tumor-specific MMP-dependent effects may prove more promising. Previous studies and our preliminary data show that exposure of mammary epithelial cells to selected MMPs causes cleavage of a cell surface molecule that stimulates cellular production of reactive oxygen species (ROS). MMP-dependent production of ROS causes cells to undergo epithelial-mesenchymal transition (EMT), a fundamental phenotypic alteration associated with progression to metastasis, and compromises the cellular genomic stability. Our long-term objective is to identify the specific steps associated with the MMP-induced malignant transformation so as to determine potential points for therapeutic intervention. To do this, we propose (1) to identify the proteolytic target of MMPs that stimulates the development of ROS, (2) to determine roles of transcription factors Snail and Twist in MMP/ROS-induction of EMT, and (3) to define how MMP/ROS stimulate genomic instability. In Aim 1, investigations of the specific role of cleavage of E-cadherin by MMPs will be supplemented by a proteolytic screen for additional/alternative targets. In Aim 2, we will identify the MMP-induced factors responsible for the increased expression of Snail and Twist, and will dissect the relative role of these transcription factors on the MMP-induced EMT. In Aim 3, we will examine how MMP/ROS induce cellular aneuploidy and mitotic abnormalities through stimulation of centrosome amplification. We expect that by elucidating the chain of events in the induction of EMT and genomic instability by MMPs, we will be able to identify novel promising points for therapeutic intervention in breast cancer.